Adjustable (differential) actuation value pressure switch



Jan. 31, 1967 Q R. SlMONlN, JR 3,301,977

ADJUSTABLE (DIFFERENTIAL) ACTUATION VALUE PRESSURE SWITCH Filed Feb. 23,1965 2 Sheets-$heet 2 r/a F526. 4. 69 I '7 Fl H hhhlfl INVENTOR. REA/E5/M0/w/v, Je.

5y /-//5 A77ae/v5ys HA/aQ/s, MECH, RUSSELL 6c KEEN United States PatentOflice 3,301,977 Patented Jan. 31, 1967 3,301,977 ADJUSTABLE(DIFFERENTIAL) ACTUATION VALUE PRESSURE SWITCH Rene Simonin, Jr.,Downey, Calif., assignor to Barksdale Valves, Los Angeles, Calif., acorporation of California Filed Feb. 23, 1965, Ser. No. 434,520 4Claims. (Cl. 20082) This invention relates to the switch art and moreparticularly to adjustable differential actuation value pressureswitches. I

It is frequently necessary or desirable to provide electrical switcheswhich are actuated in response to a predetermined chan-ge in fluidpressure. Such a pressure switch will usually include a pressureresponsive element operable to open or close a switch in response to apredetermined pressure change. For some applications, it is desired touse such a pressure switch which will, for example, open at a givenpressure level and close at a pressure level somewhat below the openingpressure. It is such a differential pressure switch having means foradjusting the opening and closing pressures that is described andclaimed herein.

It is an object of this invention to provide a completely adjustabledifferential pressure switch, the adjustments on Which may be quicklyand easily accomplished by control knobs preferably extending outside ofthe housing.

Another object of this invention is to provide a pressure switch inwhich the movements of the switch blade between an open and a closedposition are controlled by a pressure responsive actuator which movesthe entire switch.

A further object of this invention is to provide a pressure switch inwhich a switch blade is normally biased to one position and a pressureresponsive actuator restr'ains the biasing means and moves the entireswitch to cause the switch blade to move to a second position.

A'further object of this invention is to provide a pressure switch inwhich the settings which actuate the opening and closing thereof areadjustable by adjusting a limit .Of travel of the switch and theposition of an abutment relative to the switch.

A still further object of this invention is to provide a pressure switchin which the switch causing opening and closing of the electricalcircuit is adjustable by adjusting the limit of travel of the switch toestablish a decreasing pressure setting and the position of a flangeabutment relative to the switch to establish an increasing pressuresetting.

Another object of this invention is to provide novel linkages anddetails of construction for an adjustable differential pressure switch.

Briefly stated, the objects of the invention may be accomplished byproviding a support and a manual reset switch mounted for movementrelative to the support and having a switch blade movable between afirst position and a second position. Restrainable means engage theswitch blade and bias it to a first position. Actuator means responsiveto fluid pressure are operable to restrain the restrainable means frombiasing the switch blade and for moving the switch relative to thesupport. An abutment is provided in the path of movement of the switchto cause the switch blade to move to the secend position in response toa predetermined movement of the switch. According to another aspect ofthe invention, the position of the abutment relative to the switch maybe adjusted and a stop is provided to limit the travel of the switch inone direction.

The invention, both as to its organization and method of operationtogether with further objects and advantages thereof, may best beunderstood by reference to the following description taken in connectionwith the accompanying drawings.

In the drawings:

FIG. 1 is a plan view of an adjustable differential pressure switchembodying the teachings of the present invention;

FIG. 2 is an enlarged fragmentary elevational view taken along line 2-2in FIG. 1;

FIG. 3 is a partial sectional view taken along line 33 of FIG. 1;

FIG. 4 is a simplified partial sectional'vie-w similar to FIG. 3 showingthe actuator rod just after it engages the restraining means;

FIG. 5 is -a partial sectional view similar to FIG. 4 showing the switchmoved slightly upwardly by the actuator rod in response to an increasingfluid pressure; and

FIG. 6 is a partial sectional view similar to FIG. 4 showing the switchblade just after it has been snapped to the second position.

With reference to FIGS. 1 and 3, an adjustable differential pressureswitch 11 is shown. The adjustable differential pressure switch 11includes a body or housing 13 having a cover, top wall or support 15secured to the upper end thereof by a pair of screws 17, a chamber 19,and a stepped bore or spring cavity 21. The body 13 also includes afitting or end portion 23 and a main body 24 secured together by screws25. A threaded pressure sensing port 27 and an axially aligned smallorifice 29 expose a cylinder or fitting bore 31 to a source of varyingfluid pressure.

Slidably mounted in the fitting bore 31 is a piston 37 having a groove39 for an O-ring 41 and a back-up ring 43. Thus fluid pressure passingthrough the pressure sensing port 27 and the orifice 29 may act on aface 45 of the piston 37, but such fluid under pressure is prevented bythe O-ring 41 and the back-up ring 43- from entering the spring cavity21 of the body 13. Another O-ring 46 seals the interface between the endportion 23 and the main body 24.

An actuator rod 47 abuts a back face 49 of the piston 37 and rests on aseat 51 in the position shown in FIG. 3. The actuator rod 47 may be ofvarious shapes but preferably has a flange 53 against which a coilspring 55 may abut to force the latter into a seating relationship withthe seat 51. An end 57 of the actuator rod 47 extends upwardly into thechamber 19. Thus, fluid pressure acting through the pressure sensingport 27 will tend to force the piston 37 and the actuator rod 47upwardly against the resilient force of the coil spring 55.

A switch preferably a manual reset switch 59 is mounted in the chamber19 at one end by a spring bracket 61 which is secured to the support 15by a plurality of rivets 63. The spring bracket 61 is preferably curvedand possesses suflicient resilience to allow movement of the switch 59in a manner hereinafter described.

The other end of the switch 59 has an apertured plate 6 5 which receivesa bushing 66 having a flange 66a and a flange 67 spaced by and integralwith a tube portion 67a. The apertured plate 65 slidably receives thetube portion 67a of the bushing 66. The bushing 66 is slidably mountedon a threaded decreasing pressure or low level adjusting screw 69 by anut or stop 71 which halts downward motion of the switch 59. A threadedselflocking nut 73 which is secured to the support 15 threadedlyreceives the decreasing pressure adjusting screw 69 to hold the latterin the properly adjusted position, and a coil spring 75 which surroundsthe adjusting screw 69 urges the switch 59 downwardly against the stop71. Thus, the bushing 66, the adjusting screw 59 and the spring bracket61 mount the switch 59 for movement along a path and the spring bracket61 and the spring 75 constitute switch biasing means for urging theswitch 59 in one direction along said path.

The switch 59 includes a switch housing 77, a bracket 79, a low level ordecreasing pressure button 81, and an increasing pressure or high levelbutton 83. A lever 85 having a screw 87 threadedly secured in one endthereof is pivotally mounted to the bracket 79, the other end 88 of thelever being urged by a spring 89 into engagement with the decreasingpressure button 81. Both the buttons 81 and 83 are telescopicallyreceived by the switch housing 77 and are operative to urge a switchblade 91 (shown somewhat diagrammatically in FIGS. 4 through 6) betweena pair of fixed contacts 93 and 95, i.e., movement of the decreasingpressure button 81 inwardly into the switch housing 77 operates to urgethe switch blade 91 into engagement with the fixed contact 95.Conversely, movement of the increasing pressure button 83 inwardly intothe switch housing 77 causes the switch blade 91 to move into engagementwith the fixed contact 93. The buttons 81 and 83 may or may not engagethe switch blade 91. The details of a manual reset switch constructionwhich allows buttons such as the buttons 81 and 83 to move a switchblade between fixed contacts are well known in the prior art and are notdiscussed in detail herein.

The switch 59 being of the manual reset type employs a switch bladewhich will snap into engagement with a fixed contact when it is urgedbeyond a given point. It should be understood that engagement of theswitch blade 91 with either of the fixed contacts 93 or 95 may beoperative to either open or close the switch, or both of the contacts 93and 95 may complete separate external circuits.

Thus, with the elements of the adjustable differential pressure switch11 disposed as shown in FIG. 3, the spring 89 pivots the end 88 of thelever 85 into engagement with the decreasing pressure button 81. Theforce of the spring 89 moves the decreasing pressure button 81 inwardlyinto the switch housing 77 to urge the switch blade 91 upwardly intoengagement with the fixed contact 95. Thus, this pivotally mountedlevers arrangement and the button 81 constitute restrainable means forbiasing the switch blade 91 into a first position.

An adjustable abutment is mounted on the support 15 and is responsive tomovements of the switch 59 for urging the switch blade 91 to a secondposition in which it engages the fixed contact 93. A flange or abutment97 is formed at one end of a plunger 98 which extends through thesupport 15 and is biased to the right by a coil spring 99 which canexert a force sufficient to cause the switch blade 91 to snap intoengagement with the fixed contact 93. In the positions of FIGS. 3 and 4the abutment 97 is spaced from the button 83. An internally threadedtube 101 is welded to the support 15 and receives a threaded high levelor increasing pressure adjusting knob 103 in which the plunger 98 isslidably mounted. A nut 106 in a recess 107 in the adjusting knob 103limits movement of the plunger 98 to the right under the force of thespring 99. The recess 107 is closed by a cap 108 and a skirt 109 issecured to the adjustment knob 103 and extends toward the support 15.Thus, by rotating the adjustment knob 103, the position of the flange 97with respect to the support 15 and the switch 59 can be varied.

Means are also provided to house the terminals of the switch. A terminalhousing section 111 (FIG. 1) which is preferably integral with the body13 and has a removable cover 113 is provided. A plurality of terminals115, at least some of which are suitably electrically connected to thefixed contacts 93 and 95, and to a common terminal 116 by electricalconnections (not shown), are provided within the terminal housing 111.Thus, the terminals 115 may be used to connect the pressure switch 11 toan external circuit.

The operation of the device is as follows:

The pressure switch 11 is first connected by means of the pressuresensing port 27 to a source of fluid pressure, the pressure changes ofwhich are to control the switch 59. When the pressure is at somepredetermined low level, the elements of the present invention will bedisposed as shown in FIG. 3. Thus, the spring 89 acts through the leverto hold the switch blade 91 in a first position in engagement with thefixed contact and the switch 59 is resiliently held in a first locationabutting the stop 71. As the pressure sensed through the port 27increases, the piston 37 will move to the left as viewed in FIG. 3,thereby forcing the end 57 of the actuator rod 4 7 to the left. As thepressure continues to increase, the piston 37 and the actuator rod 47continue their leftward movement until the end 57 engages the screw 87in the lever 85 and urges the latter against the force of the spring 89to pivot counterclockwise as shown in FIG. 4. At this point it should benoted that FIGS. 4 through 6 are provided only to clearly show theoperation of the pressure switch and, accordingly, the constructionshown therein is simplified from that depicted in FIGS. 1 through 3.With further increases in pressure, the lever 85 will be rotated untilthe screw 87 abuts the switch housing 77 (FIG. 5) and the lever 85 nolonger urges the button 81 to bias the switch blade 91 against the fixedcontact 95. The switch blade 91, however, remains in engagement with thefixed contact 95.

Additional pressure increase causes the actuator rod 47 to urge theswitch 59 to the left against the force of the spring bracket 61 and thecoil spring 75 until the button 83 contacts the abutment 97. The spring99 affords sufficient resistance to the leftward movement of theincreasing pressure button 83 to arrest it. Accordingly, additionalleftward movement of the switch 59 causes relative movement between thelatter and the button 83 to thereby effect movement of the switch blade91 into engagement with the fixed contact 93 (FIG. 6).

Thus, when the switch 59 is moved to this second location, it moves theswitch blade 91 to a second position.

Upon a reduction in fluid pressure, the spring 55 will move the piston37 and the actuator rod 47 to the right, thereby allowing the springbracket 61 and the coil spring 75 to move the switch 59 a correspondingdistance to the right. As the pressure continues to decrease, the plate65 on the switch housing 77 will engage and come to rest back at thefirst location on the stop 71, thereby arresting the rightward movementof the switch 59. The switch blade 91 remains in the second position incontact with the fixed contact 93 until the actuator rod 47 has movedstill further to the right to allow the spring 89 to force the lever 85and the low level button 81 clockwise to snap the switch blade to theposition shown in FIG. 4, i.e., in engagement with the fixed contact 95.

It is apparent that a higher pressure is required to move the switchblade from the fixed contact 95 to the fixed contact 93 than to move theswitch blade from the contact 93 to the contact 95. That is, to move theswitch blade 91 into engagement with the fixed contact 93, the pressuresensed at the port 27 must be sufficiently great to move the piston 37and the switch 59 to the far leftward position shown in FIG. 6. However,to move the switch blade 91 back into engagement with the fixed contact95, the pressure at the port 27 must be reduced sufficiently to allowthe switch 59 to come to rest against the stop 71 and to allow the lever85 to rotate a sufiicient distance to return the switch blade to thefixed contact 95.

The pressure at which the switch blade 91 moves from one fixed contactto the other is completely adjustable in the following manner. Toincrease the pressure at which the switch blade moves from the fixedcontact 95 to the fixed 'contact 93, the adjustment knob 103 is screwedto the left away from the support 15, thereby moving the flange 97outwardly, away from the button 83 and toward the support 15. Thus, theswitch 59 must move further to the left before the button 83 engages thefiange'97 so that further leftward movement of the switch 59 will movethe switch blade 91 to the position shown in FIG. 6. Of course, turningthe adjusting knob 103 in the opposite direction will reduce thepressure required to move the switch blade 91 to the position shown inFIG. 6.

To adjust the decreasing pressure or the pressure at which the switchblade 91 is forced from the fixed contact 93 to the fixed contact 95,the low level adjusting screw 69 is turned to move the stop 71. Turningthe adjusting screw 69 inwardly or to the right reduces the pressurerequired to move the switch blade 91 to the position shown in FIG. 4 andmoving the adjusting screw to the left has the opposite eifect. Thus,the pressures at which the switch 59 is operable are completely andquickly adjustable by turning the appropriate controls which arepositioned external to the body 13.

Another important feature of this invention is the provision of a dialwhich permits the user of the pressure switch 11 to read the pressuresat which the switch 59 will operate. In FIG. 2, a transparent window 121is provided with markings to indicate numerous pressure settings. Theswitch 59 is provided with an extended portion 123 (FIG. 3) having aline or narrow fiange 125 thereon which extends to a point closelyadjacent the window 121 and is visible through the latter as shown inFIG. 2. Thus, the decreasing pressure setting and any pressuresthereabove to which the switch 59 may be exposed are determinable by thereadings appearing at the window 121. Suitable calibrations may also beprovided for example on the tube 101 to indicate the increasing pressuresetting.

Many changes, modifications, and substitutions may be made by one havingordinary skill in the art without departing from the spirit and scope ofthe invention.

What is claimed is:

1. A diiferential pressure switch exposed to varying fluid pressurescomprising:

a support;

a switch mounted for movement toward and away from said support andhaving a switch blade movable be tween a first position and a secondposition;

switch biasing means biasing said switch away from said support;

restrainable means biasing said switch blade to said first position;

means responsive to the pressure rising to a first level for restrainingsaid restrainable means from biasing said switch blade; I

actuator means responsive to pressures above said first level for movingsaid switch against the force of said switch biasing means toward saidsupport;

an abutment mounted on said support;

means movable with said switch into engagement with said abutment formoving said switch blade into said second position after said engagementoccurs; and

means to adjust the position of said abutment relative to said supportto thereby adjust the pressure at which said switch blade is moved intosaid second position.

2. A differential pressure switch exposed to varying fluid pressurescomprising:

a support;

a switch mounted for movement toward and away from said support andhaving a switch blade movable between a first position and a secondposition;

a stop secured to said support;

switch biasing means biasing said switch away from said support and intoengagement with said stop;

restrainable means biasing said switch blade to said first position;

means responsive to the pressure rising to a first level for restrainingsaid restrainable means from biasing said switch blade;

actuator means responsive to the pressure rising above said first levelfor moving said switch out of engagement with said stop against theforce of said switch biasing means toward said support;

means moving said switch blade to said second position in response to apredetermined movement of said switch toward said support; and

means to adjust the distance between said stop and said support.

3. A diiferential pressure switch exposed to varying fluid pres-sures,comprising:

a support;

a switch movably secured to said support and having a switch blademovable between a first position and a second position;

means urging said switch blade to said first position when the pressureis below a first level;

pressure responsive means moving said switch toward said support along apredetermined path from a first location to a second location when thepressure increases to a second level;

a stop spaced from and secured to said support, said first locationbeing defined by the engagement of said switch and said stop, saidsecond location being nearer said support than said first location;

abutment means mounted on said support for urging said switch blade tosaid second position when said switch is in said second location;

resilient means moving said switch against the force of said pressureresponsive means from said second location to said first location whenthe pressure decreases to an intermediate level;

means adjusting the distance between said stop and said support therebyadjusting the disposition of said first location and the value of saidintermediate level of pressure; and

means adjusting the distance between said abutment means and saidsupport thereby adjusting the disposition of said second location andthe second pressure level.

4. A differential pressure switch exposed to varying fluid pressurescomprising:

a housing having a cylinder and a chamber;

a fluid pressure responsive piston mounted for movement in saidcylinder;

an actuator rod movable in response to said piston and extending fromsaid piston toward said chamber;

a switch housing having a switch blade movable between a first positionand a second position and mounted to a wall of said chamber, said switchhousing being movable by said actuator rod from a first location to asecond location;

a stop secured to said wall of said chamber;

means to adjust the distance between said stop and said wall;

first resilient means urging said switch away from said wall and intoengagement with said stop to define said first location of said switchhousing;

an abutment secured to said wall;

means to adjust the distance between said wall and said abutment;

a lever pivotally mounted intermediate its ends to said switch housing,one of said ends being engageable by said actuator rod;

first button means on said switch housing movable to urge said switchblade to said first position, said button means being engageable by theother end of said lever;

7 8 second resilient means rotating said lever so that said ReferencesCited by the Examiner other end engages said first button means to moveUNITED STATES PATENTS Said SWIICh blade to sa1d first POSltlOIl; and2583397 1/1952 Strysko second button means in sa1d switch housingcooperat- 2 803 718 5 J 1 mg with sand abutment in said second locationof said housing for urging said switch blade to said BERNARD GILHEANY P1mm) Examiner second position. H. B. GILSON, G. MAIER, AssistantExaminers.

9/1957 Bloom et a1 2005-82

1. A DIFFERENTIAL PRESSURE SWITCH EXPOSED TO VARYING FLUID PRESSURESCOMPRISING: A SUPPORT; A SWITCH MOUNTED FOR MOVEMENT TOWARD AND AWAYFROM SAID SUPPORT AND HAVING A SWITCH BLADE MOVABLE BETWEEN A FIRSTPOSITION AND A SECOND POSITION; SWITCH BIASING MEANS BIASING SAID SWITCHAWAY FROM SAID SUPPORT; RESTRAINABLE MEANS BIASING SAID SWITCH BLADE TOSAID FIRST POSITION; MEANS RESPONSIVE TO THE PRESSURE RISING TO A FIRSTLEVEL FOR RESTRAINING SAID RESTRAINABLE MEANS FROM BIASING SAID SWITCHBLADE; ACTUATOR MEANS RESPONSIVE TO PRESSURES ABOVE SAID FIRST LEVEL FORMOVING SAID SWITCH AGAINST THE FORCE OF SAID SWITCH BIASING MEANS TOWARDSAID SUPPORT;